In high voltage metal-oxide-semiconductor field-effect transistor (MOSFET) devices, high breakdown voltage (BV) and low on-resistance (RON) are generally desirable characteristics. However, both of these characteristics typically depend on the thickness and resistance of a device's drift region. Typically, both of these characteristics increase as the dopant concentration decreases or the thickness increases. In order to lower RON while maintaining BV, Reduced Surface Field (RESURF) technology may be employed. For example, RESURF devices may operate with a reduced maximum electric field within the drift region due to use of multiple depletion regions between the drift and source regions.
Super junction device 100 of FIG. 1 is one example of a RESURF device. As shown, device 100 includes N+ region 10, drift region 11, P source regions 12, N+ source regions 13, and gates 14. In device 100, drift region 11 includes a super junction structure including N stripes 111 alternated with P stripes 112. The alternation of N stripes 111 with P stripes 112 may enable lateral depletion while allowing doping concentration of drift region 11 to be relatively great (e.g., for a relatively low RON) for a given BV. However, fabrication of super junction device 100 may be relatively difficult. For example, it may be difficult to accurately fabricate stripes in drift region 11.